JP6195710B2 - Engine control device for construction machinery - Google Patents

Description

  The present invention relates to an engine control device for a construction machine, and more particularly to an engine control device for a construction machine that drives a hydraulic pump that supplies hydraulic oil to a working device with an engine output.

  2. Description of the Related Art Conventionally, construction machines such as a hydraulic excavator that includes a hydraulic pump that supplies hydraulic oil to a plurality of actuators that operate a front work machine and that drives the hydraulic pump with an engine output are known. Such a hydraulic excavator is disclosed in Patent Document 1, for example.

  Generally, a hydraulic excavator is provided with an engine controller that performs various types of engine control and a vehicle body controller that performs various types of control on the construction machine side. These engine controllers and the vehicle body controller are connected to each other via CAN communication. ing. Then, the target engine speed required by the construction machine side (particularly, the hydraulic pump) is input from the vehicle body controller to the engine controller, and the fuel injection amount is determined based on the deviation between the target engine speed and the actual engine speed. Feedback control.

JP 2000-145720 A

  By the way, when the feedback control of the fuel injection amount as described above is performed, the control by the vehicle body controller and the engine controller is processed in the following order. 1) Front work machine is activated, 2) Increase in engine load requirement, 3) Decrease in engine speed, 4) Increase in fuel injection amount, and 5) Adjust fuel injection amount to target actual engine speed. It converges to the rotation speed.

  That is, in the feedback control, the increase in the fuel injection amount according to the required load is executed after the engine speed has decreased. Therefore, at the start of the operation of the front working machine, there is a problem that a phenomenon of lowering the engine speed (hereinafter, this phenomenon is also referred to as lag down) is caused, and the workability of the construction machine is deteriorated. In order to reduce such lag down, it is necessary to adjust control parameters such as increasing the gain of PID control. In this case, however, there is a problem that the fluctuation of the fuel injection amount becomes large even in a steady load state. .

  The present invention has been made in view of the above points, and an object of the present invention is to provide an engine control device for a construction machine that can effectively reduce the lag down caused when the required load of the engine increases. There is.

In addition, an engine control device for a construction machine that drives a hydraulic pump that supplies hydraulic oil to a work machine with the output of an engine and feedback-controls the fuel injection amount of the engine based on a deviation between an actual rotational speed and a target rotational speed. And a required load calculation means for calculating, as a required load, an output of the engine required to drive the hydraulic pump according to the operation of the work implement, and an engine controller, When the required load is calculated by the required load calculating means, a feedforward control means for adding a fuel injection increase amount set in advance according to the required load to the fuel injection amount of the engine, and fuel injection by the feedforward control means If the deviation between the peak value of the actual rotation speed and the target rotation speed exceeds the predetermined judgment threshold when the amount is increased, Includes an injection quantity correcting means for reducing corrects the fuel injection increase amount set because, wherein the engine controller is to store the relationship between the required load and the fuel injection increase amount in advance, the injection quantity correcting means, the actual rotation speed When the deviation between the peak value of the engine and the target rotational speed exceeds the determination threshold, the relationship is corrected so that the fuel injection increase amount for the same required load becomes small.

In addition, an engine control device for a construction machine that drives a hydraulic pump that supplies hydraulic oil to a work machine with the output of an engine and feedback-controls the fuel injection amount of the engine based on a deviation between an actual rotational speed and a target rotational speed. A vehicle body controller including a required load calculating means for calculating, as a required load, an output of the engine required to drive the hydraulic pump according to the operation of the work implement; and the required load is calculated by the required load calculating means. When the fuel injection amount is increased by the feedforward control means for adding the fuel injection increase amount set in advance according to the required load to the fuel injection amount of the engine when calculated, and when the fuel injection amount is increased by the feedforward control means, When the deviation between the peak value of the actual rotational speed and the target rotational speed exceeds a predetermined determination threshold, it is necessary to reduce and correct the calculated required load. A load correction means, wherein the vehicle controller previously stores a relationship of the load parameter and the required load, the required load compensation means are included in the said vehicle controller, the peak value of the actual rotational speed and the target rotational speed When the deviation exceeds the determination threshold, the relationship is corrected so that the required load for the same load parameter is reduced.

  According to the engine control device for a construction machine of the present invention, it is possible to effectively reduce the lag down caused when the required load of the engine increases.

1 is a schematic side view of a construction machine to which an engine control device according to an embodiment of the present invention is applied. It is a typical whole block diagram which shows the engine control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the rotation speed setting map of the engine control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the required load setting map of the engine control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the injection increase amount map of the engine control apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the control content by the vehicle body controller of the engine control apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the control content by the engine controller of the engine control apparatus which concerns on one Embodiment of this invention. (A) is a time chart which shows the injection control by the engine control apparatus which concerns on one Embodiment of this invention, (b) is a time chart which shows the injection control by the conventional engine control apparatus.

  Hereinafter, based on FIGS. 1-8, the engine control apparatus of the construction machine which concerns on one Embodiment of this invention is demonstrated. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  First, the overall configuration of a hydraulic excavator to which the engine control apparatus of the present embodiment is applied will be described with reference to FIG. The hydraulic excavator includes a lower traveling body 1 having a crawler type traveling device, an upper swing body 2 mounted on the lower traveling body 1, and a front work machine 3 provided at a front portion of the upper swing body 2. ing. Further, the front work machine 3 includes a boom 4 rotatably supported on the front part of the upper swing body 2, an arm 5 rotatably supported on the tip of the boom 4, and a tip of the arm 5. A bucket 6 rotatably attached, a boom cylinder 7 that operates the boom 4, an arm cylinder 8 that operates the arm 5, and a bucket cylinder 9 that operates the bucket 6 are provided. In the front work machine 3, hydraulic oil is supplied to each cylinder 7-9 from a main hydraulic circuit 12 (see FIG. 2), which will be described later, in response to an operation of an operation lever device 11 (see FIG. 2) provided in the cab 2a. Operates when supplied.

  Next, the overall configuration of the engine control device for a construction machine according to the present embodiment will be described with reference to FIG.

  An engine control device for a construction machine according to this embodiment includes a diesel engine (hereinafter simply referred to as an engine) 10 and a main hydraulic circuit 12 that supplies hydraulic oil to the cylinders 7 to 9 (see FIG. 1) of the front work machine 3. , An accelerator dial 17 for setting a target rotational speed of the engine 10, a work mode changeover switch 18 for selecting a work mode, and a vehicle body controller 20 and an engine controller 30 connected to each other by CAN communication so as to be able to communicate with each other.

  The main hydraulic circuit 12 is provided with a variable displacement hydraulic pump 13 that is driven by the power of the engine 10. The hydraulic pump 13 is connected to the hydraulic oil tank 14 via the first pipeline 12a, and is connected to the control valve 15 via the second pipeline 12b.

  The control valve 15 is a pilot-type flow control valve that switches the position of the spool to variably control the flow rate and flow direction of the hydraulic oil. The control valve 15 is connected to the head chamber 7a of the boom cylinder 7 through the third conduit 12c, and is connected to the rod chamber 7b of the boom cylinder 7 through the fourth conduit 12d.

  Further, a pilot pressure generation circuit (not shown) that outputs a pilot pressure corresponding to the operation amount of the operation lever device 11 is connected to both ends of the spool of the control valve 15. For example, when pilot pressure in the direction for extending the boom cylinder 7 is introduced to the control valve 15, the hydraulic oil is supplied from the hydraulic pump 13 to the head chamber 7a by movement of the spool. Thereby, the boom cylinder 7 is operated in the extending direction. Further, when pilot pressure in a direction for reducing the boom cylinder 7 is introduced to the control valve 15, hydraulic oil is supplied from the hydraulic pump 13 to the rod chamber 7b by movement of the spool. Thereby, the boom cylinder 7 is operated in the reduction direction.

  The accelerator dial 17 is a dial type switch that can adjust the target rotational speed of the engine 10 in accordance with the operation of the operator, and the set dial position is output to the vehicle body controller 20.

  The work mode switch 18 is a switch that can selectively switch the work mode of the front work machine 3 in accordance with the switching operation of the operator, and the set work mode is output to the vehicle body controller 20. In the present embodiment, selectable work modes include, for example, two types of modes: a power mode PM that improves the operability of the front work machine 3 and an eco mode EM that improves the fuel consumption of the engine 10. .

  The vehicle body controller 20 performs various controls on the vehicle body side, and includes a known CPU, ROM, RAM, input port, output port, and the like. In order to perform these various controls, output signals from various sensors such as the hydraulic sensor 19 provided in the main hydraulic circuit 12 are input to the vehicle body controller 20.

  The vehicle body controller 20 includes a target rotational speed calculation unit 21, a required load calculation unit 22, and a required load characteristic correction unit 23 as some functional elements. In the present embodiment, each of these functional elements is described as being included in the vehicle body controller 20 that is integral hardware, but any one of these functional elements may be provided in separate hardware.

The target rotational speed calculation unit 21 calculates the target rotational speed _NT of the engine 10 based on the dial position set by the accelerator dial 17 and the work mode selected by the work mode changeover switch 18. More specifically, the vehicle body controller 20 stores a rotational speed setting map that defines the relationship between the dial position of the accelerator dial 17 shown in FIG. 3 and the target rotational speed _NT of the engine 10. On the rotational speed setting map, the target rotational speed characteristic N ₁ corresponds to the power mode PM that improves the operability of the front work machine 3, and the target rotational speed characteristic N ₂ corresponds to the eco mode EM that improves fuel consumption. The target rotational speed calculation unit 21 is configured to read the target rotational speed _NT corresponding to the dial position and the work mode from the rotational speed setting map and output the target rotational speed _NT to the engine controller 30 by CAN communication. Has been.

Based on load parameters such as the operation amount of the operation lever device 11 by the discharge pressure of the hydraulic pump 13 detected by the hydraulic sensor 19 and the operation pressure detected by a pilot pressure sensor (not shown), the required load calculation unit 22 It computes the output torque of the engine 10 is consumed by the hydraulic pump 13 by the operation of the working machine 3 and the upper rotating body 2 as the required load L _R. More specifically, the vehicle body controller 20 stores a required load setting map that defines the relationship between the load parameter and the required load shown in FIG. On the required load setting map, the required load characteristic L ₁ corresponds to the power mode PM that improves the operability of the front work machine 3, and the required load characteristic L ₂ corresponds to the eco mode EM that improves the fuel consumption. Required load calculation unit 22, as well as read the required load L _R corresponding from the required load setting map to load parameters and working mode, is configured to output to the engine controller 30 to the required load L _R by CAN communication.

Required load characteristic correcting unit 23, based on the actual rotational speed N of the engine 10 when the feedforward control in accordance with the required load L _R by the engine controller 30 to be described later is executed, request the required load characteristics of the load setting map L ₁ and L ₂ are corrected. More specifically, when the feed-forward control in accordance with the required load L _R is executed, the rotational speed of the engine 10 is temporarily greatly increased after decreased (see FIG. 8 (a)). The required load characteristic correction unit 23 determines a deviation (N _MAX −N _T ) between the peak value N _MAX of the actual rotational speed N and the target rotational speed _NT during feedforward control to a predetermined determination threshold value N _V (for example, 200 rpm). If it exceeds, the slopes of the required load characteristics L ₁ and L ₂ on the required load setting map are corrected to decrease. Thereby, the overshoot of feedforward control is reduced and the deterioration of fuel consumption can be suppressed effectively.

  The engine controller 30 performs various controls of the engine 10 and includes a known CPU, ROM, RAM, input port, output port, and the like. In order to perform the various controls, output signals from various sensors such as the engine rotation sensor 40 and an accelerator opening sensor (not shown) are input to the engine controller 30.

  Further, the engine controller 30 includes a fuel injection control unit 31, a feedforward control unit 32, and an injection increase amount characteristic correction unit 33 as some functional elements. These functional elements will be described as being included in the engine controller 30 which is integral hardware in the present embodiment, but any one of them can be provided in separate hardware.

The fuel injection control unit 31 controls fuel injection with a preset basic injection amount Q according to the target rotational speed _NT input from the vehicle body controller 20 when the front work machine 3 is operated. The fuel injection control during the operation is feedback control (PID control) based on the deviation between the target rotational speed _NT input from the vehicle body controller 20 and the actual rotational speed N input from the engine speed sensor 40.

Feedforward control unit 32, based on the required load L _R inputted from the vehicle body controller 20, a feed forward control to increase the instruction signal output from the fuel injection control unit 31 to the fuel injection device (basic injection quantity Q) and Run. More specifically, the engine controller 30, the injection increase amount map that defines the relationship between the increase amount Q _R of the required load L _R and the fuel injection shown in FIG. 5 is stored. On this injection increase amount map, the injection increase amount characteristic I is set so that the increase amount Q _R increases as the required load L _R increases. Feedforward control unit 32, along with reading the increase amount Q _R corresponding to the required load L _R from the injection increase amount map, and adds the increase amount Q _R to the basic injection quantity Q (Q + Q _R). Thus, if the required load L _R of the engine 10 is increased, the fuel injection amount be increased appropriately, it is possible to reduce lowering of the engine revolution speed (the lag-down) effectively.

The injection increase amount characteristic correction unit 33 corrects the injection increase amount characteristic I on the injection increase amount map based on the actual rotational speed N of the engine 10 when the feedforward control is executed. More specifically, the injection increase amount characteristic correction unit 33 determines that the deviation (N _MAX −N _T ) between the peak value N _MAX of the actual rotational speed N and the target rotational speed _NT during the feedforward control is a predetermined determination threshold value N _V ( For example, when it exceeds 200 rpm, the inclination of the injection increase amount characteristic I on the injection increase amount map is corrected to decrease. Thereby, the overshoot of feedforward control is reduced and the deterioration of fuel consumption can be suppressed effectively.

  Next, a control flow by the engine control device for the construction machine according to the present embodiment will be described based on FIGS. The flowchart in FIG. 6 shows the control flow by the vehicle body controller 20, and the flowchart in FIG. 7 shows the control flow by the engine controller 30.

First, the flowchart of the vehicle body controller 20 shown in FIG. 6 will be described. In step 100 (hereinafter, step is simply described as S), the dial position of the accelerator dial 17 and the work mode (power mode PM / eco mode EM) of the work mode changeover switch 18 are confirmed. Further, in S110, based on the set dial position and the working mode, the rotation speed setting map with the target rotational speed (see FIG. 3) N _T is set, the engine controller The set target revolution speed N _T 30 is output.

  In S120, the presence or absence of the required load is determined based on load parameters such as the discharge pressure of the hydraulic pump 13 and the operation amount of the operation lever device 11. If there is a required load (YES), the control proceeds to S130.

In S130, the required load L _R is set from the required load setting map (see FIG. 4) based on the set work mode and load parameters, and the set required load L _R is output to the engine controller 30. The

In S140, the deviation of the peak value N _MAX and the target rotational speed N _T of the actual rotation speed N when the feedforward control by the engine controller 30 is executed ΔN (N _MAX -N _T) is a predetermined determination threshold value N _V It is determined whether it has been exceeded. Deviation ΔN cases greater than the judgment threshold value N _V (NO), the control is returned. On the other hand, if the deviation ΔN exceeds the determination threshold value N _V (YES), the control proceeds to S150. In S150, correction for reducing the slope of the required load characteristics L ₁ and L ₂ on the required load setting map is executed, and the present control is returned.

Next, a flowchart of the engine controller 30 shown in FIG. 7 will be described. In S200, the fuel injection of the engine 10 is feedback-controlled based on the deviation between the target rotational speed _NT and the actual rotational speed N input from the vehicle body controller 20 in S110 described above.

  In S210, it is determined whether or not the requested load is input from the vehicle body controller 20. If there is an input of the required load (YES), the control proceeds to S220. On the other hand, when there is no request load input (NO), the present control is returned to S200.

In S220, based on the required load L _R inputted from the vehicle body controller 20 at S130 described above, with increasing amount Q _R is set from the injection increase amount map, adding the increase amount Q _R to the basic injection quantity Q ( Q + Q _R ) feed forward control is executed. Further, in S230, feedback control is executed so that the deviation between the target rotational speed _NT and the actual rotational speed N becomes 0 (zero).

In S240, the actual rotational speed N is whether it converges to the target rotational speed N _T, i.e. the deviation between the target revolution speed N _T and the actual rotation speed N is 0 (zero) is determined. When the deviation becomes 0 (zero) (YES), the control proceeds to S250. On the other hand, when the deviation is not 0 (zero) (NO), the control is returned to S230.

In S250, the deviation ΔN of the peak value N _MAX and the target rotational speed N _T of the actual rotation speed N when the feedforward control is executed (N _MAX -N _T) does not exceed the predetermined determination threshold value N _V in S220 It is determined whether or not. Deviation ΔN cases greater than the judgment threshold value N _V (NO), the control is returned. On the other hand, if the deviation ΔN exceeds the determination threshold value N _V (YES), the control proceeds to S260. In S260, correction for decreasing the slope of the injection increase amount characteristic I on the injection increase amount map is executed, and the present control is returned.

  Next, the effect by the engine control apparatus of the construction machine which concerns on this embodiment is demonstrated.

In the conventional system in which fuel injection of the engine 10 is executed only by feedback control based on the deviation between the target rotational speed _NT and the actual rotational speed N, the required load of the engine 10 increases, and the fuel after the engine rotational speed has once decreased. The injection amount was increased (see t _{1 in} FIG. 8B). Therefore, (see t ₂ in FIG. 8 (b)) so-called lag-down to reduce the engine speed increases, had become a factor to deteriorate the workability of the front work machine 3 as a result. Further, since the engine speed is greatly reduced, it takes a long time for feedback control to converge the actual speed N to the target speed _NT after increasing the fuel injection amount (FIG. 8B). reference of t _3).

On the other hand, in the engine control device for a construction machine according to the present embodiment, when a required load is input from the vehicle body controller 20 to the engine controller 30, feedforward control for increasing the fuel injection amount of the engine 10 is executed at the same time. is the (see t ₁ in FIG. 8 (a)). That is, (see t ₂ in FIG. 8 (a)) but the engine speed drops only slightly, then by increasing the fuel injection amount, the engine speed is rapidly increased. As a result, the lag down is greatly reduced (about half) compared to the conventional method.

  Therefore, according to the engine control device for a construction machine according to the present embodiment, the decrease in engine speed (lag down) caused by the increase in the required load of the engine 10 can be effectively reduced, and the workability and drivability of the construction machine can be reduced. Tea can be improved effectively. In addition, since it is not necessary to increase the gain of PID control in order to reduce lag down, it is possible to suppress fluctuations in the fuel injection amount even in a steady load state.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, the construction machine is not limited to a hydraulic excavator, and can be widely applied to other construction machines such as a loader as long as it includes the hydraulic pump 13.

DESCRIPTION OF SYMBOLS 10 Engine 12 Main hydraulic circuit 13 Hydraulic pump 20 Body controller 21 Target rotation speed calculation part 22 Request load calculation part 23 Request load characteristic correction part 30 Engine controller 31 Fuel injection control part 32 Feedforward control part 33 Injection increase amount characteristic correction part

Claims (2)

An engine control device for a construction machine that drives a hydraulic pump that supplies hydraulic oil to a work machine with an engine output, and feedback-controls the fuel injection amount of the engine based on a deviation between an actual rotational speed and a target rotational speed. ,
A required load calculating means for calculating, as a required load, the output of the engine required to drive the hydraulic pump according to the operation of the work implement;
An engine controller, the engine controller comprising:
Feedforward control means for adding a fuel injection increase amount set in advance according to the required load to the fuel injection quantity of the engine when the required load is calculated by the required load calculating means;
When the fuel injection amount is increased by the feedforward control means, if the deviation between the peak value of the actual rotation speed and the target rotation speed exceeds a predetermined determination threshold, the fuel injection increase amount set in advance is decreased. An injection amount correcting means for correcting,
The engine controller stores in advance the relationship between the required load and the fuel injection increase amount, and the injection amount correction means is the same when the deviation between the peak value of the actual rotational speed and the target rotational speed exceeds the determination threshold value. An engine control device for a construction machine, wherein the relationship is corrected so that an increase in fuel injection with respect to a required load is reduced. An engine control device for a construction machine that drives a hydraulic pump that supplies hydraulic oil to a work machine with an engine output, and feedback-controls the fuel injection amount of the engine based on a deviation between an actual rotational speed and a target rotational speed. ,
A vehicle body controller including a required load calculation means for calculating, as a required load, an output of the engine required to drive the hydraulic pump according to the operation of the work implement;
Feedforward control means for adding a fuel injection increase amount set in advance according to the required load to the fuel injection quantity of the engine when the required load is calculated by the required load calculating means;
When the fuel injection amount is increased by the feedforward control means, if the deviation between the peak value of the actual rotational speed and the target rotational speed exceeds a predetermined determination threshold, the calculated required load is decreased and corrected. A required load correction means,
The vehicle body controller stores a relationship between a load parameter and a required load in advance, and the required load correction unit is included in the vehicle body controller, and a deviation between a peak value of an actual rotation speed and a target rotation speed sets the determination threshold value. An engine control device for a construction machine, wherein the relationship is corrected so that a required load with respect to the same load parameter is reduced when exceeding.

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